Comparison of general characteristics

Prospective users must understand a few foundational details when comparing Oracle’s database with the EDB Postgres Advanced Server database. Having an understanding of these basic characteristics is especially valuable during discussions between Oracle experts and Postgres experts.

Terminology

Before looking at the compatibility issues in detail, be aware that there are differences in nomenclature used in many SQL-based products. The table shows some of these differences.

Oracle	EDB Postgres Advanced Server
Table or index	Table, index, or relation
Row	Row or tuple
Column	Column or attribute
Data block	Page—When block is on disk
Page	Buffer—When block is in memory

In addition, each instance of EDB Postgres Advanced Server is referred to as a cluster. A cluster is a collection of databases that is managed by a single program instance. It consists of a data directory that contains all data and configuration files. You can refer to it in two ways: by location of the data directory or by port number. A single server can have many program installations, and you can create multiple clusters.

General capabilities

Both Oracle and EDB Postgres Advanced Server are mature, enterprise-class, object-relational databases that meet the industry standards for atomicity, consistency, isolation, and durability (ACID) compliance. Both were developed from the same IBM research on System R and designed to solve many of the same problems. These database programs have many similarities.

General capabilities	Oracle	EDB Postgres Advanced Server (EPAS)
Design origin	Commercial implementation based on IBM’s original research for System R	Academic implementation (UC Berkeley) based on IBM’s original research for System R
Continuous development	Since 1979	PostgreSQL development started in 1986. EPAS development started in 2004. EPAS is based on PostgreSQL and continuously merged.
Object relational database	Yes	Yes
Processing architecture	Process based and thread based	Process based
Full ACID compliance	Yes	Yes
Multiversion concurrency control	Yes	Yes
Multitenant architecture	Yes	Yes
Automatic workload management	Yes	No
Enterprise database management	Oracle Enterprise Manager	EDB Postgres Enterprise Manager
Multicore support	Yes	Yes
Write-ahead durability	Redo logs	Write-ahead log
Disk-read buffering	Yes	Yes

Capacities

When considering a new database, you need to understand whether a new solution has the capacity to support existing application data designs, workloads, and anticipated growth. Applying the capacity of a new solution to your workloads and future applications means understanding how it supports data across multiple structures in the database.

Capacities	Oracle	EDB Postgres Advanced Server
Max. database size	Unlimited	Unlimited
Max. table size	4 GB x Block Size	32 TB
Max. row size	4 TB	1.6 TB
Max. field size	For BLOB(4 GB - 1) x DB_BLOCK_SIZE initialization parameter	1 GB
Max. rows per table	Unlimited	Unlimited
Max. columns per table	1000	250 - 1600 depending on column types
Max. indexes per table	Unlimited	Unlimited